Cardiovascular disease (CVD) is the leading cause of death and disability in the United States, affecting more than 81 million American adults. It is well established that risk factors such as hypertension, diabetes, and hyperlipidemia not only place individuals at risk for CVD, but also place them at risk for neurocognitive impairment and dementia. CVD risk factors have been shown to be associated with a cascade of neurophysiologic and neuroanatomic changes (e.g., narrowing of the small arteries in the subcortical regions of the brain, reduced cerebral blood flow, disruption of the blood-brain barrier), resulting in cognitive impairment and dementia. Patients with CVD risk factors who exhibit cognitive impairment without dementia (CIND) are considered to be in a transition stage between normal aging and early dementia. There is great interest in CIND because longitudinal studies have documented that such individuals are highly vulnerable to developing dementia. Exercise and diet have been shown to improve CVD risk factors and also appear particularly promising lifestyle approaches for preventing dementia. In this application, we propose a randomized clinical trial of patients with CVD risk factors who also are characterized by subjective cognitive complaints and objective evidence of neurocognitive deficits without dementia (CIND). A 2 by 2 design is proposed to examine the independent and combined effects of diet and exercise on neurocognition. Participants will be randomly assigned to 6 months of aerobic exercise, dietary modification using the DASH diet, or a combination of both exercise and diet; a fourth (control) group will receive health education but otherwise will maintain their usual dietary and activity habits. The study will aim to (a) evaluate the effectiveness of aerobic exercise and the DASH diet in improving neurocognitive functioning in patients with CVD risk factors and CIND; (b) examine possible mechanisms by which exercise and diet improve neurocognition; and (c) consider potential moderators of treatment, including subclinical CVD. These data will have important clinical significance by determining the extent to which lifestyle may improve neurocognition in patients vulnerable to neurocognitive decline and will identify key vascular and related biomarkers that may account for improved neurocognition among persons with CIND.